Method and apparatus for supporting segmentation of packets for uplink transmission

ABSTRACT

A method and apparatus for segmenting medium access control (MAC) service data units (SDUs) creates enhanced MAC-es PDUs in the enhanced MAC-e/es sub-layer by concatenating MAC SDUs received from the logical channels. An enhanced transport format combination (E-TFC) selection entity controls the concatenation of MAC SDUs into enhanced MAC-es PDUs. When a MAC SDU is received that is too large to fit into a selected enhanced MAC-es PDU payload, a segmentation entity segments the MAC SDU such that the MAC SDU segment fills the remaining payload available in the selected enhanced MAC-es PDU. The enhanced MAC-es PDU is then assigned a transmission sequence number (TSN) and multiplexed with other enhanced MAC-es PDUs to create a single enhanced MAC-e PDU that is transmitted on the E-DCH in the next transmission time interval (TTI). A HARQ entity stores and, if necessary retransmits the enhanced MAC-e PDU when a transmission error occurs.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/339,146, filed Jul. 23, 2014, which is a continuation of U.S. patentapplication Ser. No. 13/423,628, filed Mar. 19, 2012, which issued onAug. 26, 2004 as U.S. Pat. No. 8,817,781, which is a continuation ofU.S. patent application Ser. No. 12/238,599, filed Sep. 26, 2008, whichissued on Mar. 20, 2012 as U.S. Pat. No. 8,139,609, which claims thebenefit of U.S. Provisional Application No. 60/975,596 filed Sep. 27,2007, the contents of which are hereby incorporated by reference herein.

FIELD OF INVENTION

This application is related to wireless communications.

BACKGROUND

The third generation partnership project (3GPP) Release 6, introducedhigh-speed uplink packet access (HSUPA) to provide higher data rates foruplink transmissions. As part of HSUPA, a new transport channel, theenhanced dedicated channel (E-DCH), was introduced to carry uplink (UL)data at higher rates. Along with the E-DCH, new MAC sub-layers wereintroduced within the overall wireless transmit/receive unit (WTRU) tocontrol the E-DCH transport channel. The new MAC sub-layer is theMAC-e/es. More specifically, the MAC-e/es is the MAC entity that handlesthe data transmitted on the E-DCH. Upper layers configure how theMAC-e/es is to be applied to handle E-DCH functionality.

A block diagram of the UMTS Terrestrial Radio Access Network (UTRAN)MAC-e layer architecture is shown in FIG. 1, a block diagram of the UMTSTerrestrial Radio Access Network (UTRAN) MAC-es layer architecture isshown in FIG. 2, and a block diagram of the WTRU MAC-e/es layerarchitecture is shown in FIG. 3.

For each WTRU that uses the E-DCH, one MAC-e entity per NodeB and oneMAC-es entity in a serving radio network controller (SRNC) areconfigured.

FIG. 1 shows a UTRAN MAC-e 100 and a E-DCH scheduling entity 110. TheMAC-e 100 is located in a NodeB and controls access to the E-DCH. Thereis one MAC-e 100 in the NodeB for each WTRU. There is only one E-DCHscheduling entity 110 in the NodeB. The E-DCH scheduling entity 110manages E-DCH cell resources between WTRUs.

The UTRAN MAC-e 100 shown in FIG. 1 comprises an E-DCH control entity120, a de-multiplexing entity 130, and a hybrid automatic retransmissionrequest entity (HARQ) entity 140. The MAC-e 100 and the E-DCH schedulingentity 110 handle HSUPA specific functions in the NodeB.

The UTRAN MAC-es 200 shown in FIG. 2 comprises a reordering queuedistribution entity 210, a reordering/combining entity 220, and adisassembly entity 230. The UTRAN MAC-es 200 further comprises a macrodiversity selection entity in FDD mode when there is soft handover withmultiple NodeBs. The MAC-es 200 is located in the SRNC and handles E-DCHspecification functionality that is not covered in the MAC-e in theNodeB. The MAC-es 200 is connected to both the MAC-e and the MAC-d.

FIG. 3 shows a block diagram of the WTRU MAC-e/es layer architecture.The WTRU MAC-e/es 300 comprises a HARQ entity 310, a multiplexing andtransmission sequence number (TSN) setting entity 320, and an enhancedtransport format combination (E-TFC) selection entity 330.

The HARQ entity 310 handles the MAC functions relating to the HARQprotocol. Specifically, the HARQ entity 310 is responsible for storingMAC-e payloads and re-transmitting them. The detailed configuration ofthe HARQ protocol is provided by the radio resource control (RRC) overthe MAC-control service access point (SAP).

The multiplexing and TSN setting entity 320 concatenates multiple MAC-dprotocol data units (PDUs) into MAC-es PDUs. Further, the multiplexingand TSN setting entity 320 multiplexes one or more MAC-es PDUs into asingle MAC-e PDU, to be transmitted in a next transmission time interval(TTI), as instructed by the E-TFC selection entity 330. The multiplexingand TSN setting entity 320 is also responsible for managing and settingthe TSN per logical channel for each MAC-es PDU.

The E-TFC selection entity 330 is responsible for E-TFC selectionaccording to scheduling information, relative grants and absolutegrants, received from the UTRAN via L1 signaling and a serving grantvalue signaled through RRC. The E-TFC selection entity 330 is alsoresponsible for arbitration among the different flows mapped on theE-DCH. The detailed configuration of the E-TFC selection entity 330 isprovided by RRC over the MAC-control SAP. As stated above, the E-TFCselection entity 330 controls the multiplexing function of themultiplexing and TSN setting entity 320.

Currently, the MAC-e/es selects a number of MAC service data units(SDUs) from each logical channel and multiplexes the MAC SDUs into asingle MAC-e PDU for transmission. The existing MAC-e/es protocol relieson the fact that the RLC is configured to deliver PDUs in one or morepredefined sizes. Unfortunately, the use of predefined PDU sizes createsoverhead at higher data rates.

Accordingly, there exists a need for improved MAC-e/es architecture inboth the UTRAN and WTRU that allows for flexible PDU sizes at the radiolink control (RLC) layer and PDU segmentation at the MAC layer. The useof flexible PDU sizes and PDU segmentation would allow for higher datarates in the UL and may reduce header overhead for UL transmissions.

SUMMARY

Service data units (SDUs) containing data submitted to the MAC sub-layerare created by higher layers. When the WTRU is configured to use theE-DCH, the MAC SDU is passed to the enhanced MAC-e/es sub-layer in theWTRU, which controls data transmitted on the E-DCH. Enhanced MAC-es PDUsare created in the enhanced MAC-e/es sub-layer by concatenating MAC SDUsreceived from the logical channels. The enhanced MAC-es PDUs areassigned a transmission sequence number (TSN) and then multiplexed intoa single enhanced MAC-e PDU for transmission on the E-DCH. An enhancedtransport format combination (E-TFC) selection entity controls theconcatenation of MAC SDUs into enhanced MAC-es PDUs. When a MAC SDU isreceived that is too large to fit into a selected enhanced MAC-es PDUpayload, a segmentation entity segments the MAC SDU such that the MACSDU segment fills the remaining payload available in the selectedenhanced MAC-es PDU. The enhanced MAC-es PDU is then multiplexed withother enhanced MAC-es PDUs to create a single enhanced MAC-e PDU that istransmitted on the E-DCH in the next TTI. A HARQ entity stores and, ifnecessary retransmits the enhanced MAC-e PDU when a transmission erroroccurs.

When a MAC SDU is segmented, the remaining segment of the MAC SDU thatis not included in the next enhanced MAC-es PDU may be stored in asegmentation buffer or segmentation entity. The stored remaining segmentis then included in a subsequent enhanced MAC-es PDU. For a subsequenttransmission, if the remaining segment of MAC SDU is too large for theenhanced MAC-es payload, this remaining segment may be segmented again.In an embodiment, buffered MAC SDU segments are given priority whenenhanced MAC-es PDUs are being created. Segmentation entities areemptied before more information is requested from the logical channelsfor inclusion in a MAC-es PDU. A segmentation entity may be provided foreach logical channel, or alternatively, a single segmentation entity maybe provided for storing MAC-d PDU segments for all logical channels. Inthe latter, only segments from one logical channel may be stored in thesegmentation entity at a time. No other segmentation processes shouldtake place for another logical channel until the data in thesegmentation entity is transmitted. When segmentation occurs, theenhanced MAC-es PDU may include a segmentation description in additionto the TSN. The segmentation description indicates whether a segment isincluded in the enhanced MAC-es PDU and whether there are more segmentsto follow.

In the UTRAN, enhanced MAC-e PDUs containing MAC SDUs or segmentsthereof are de-multiplexed into enhanced MAC-es PDUs at the enhancedMAC-e sub-layer located in the NodeB. After de-multiplexing, theenhanced MAC-es PDUs are processed in the enhanced MAC-es sub-layerlocated at the RNC. The enhanced MAC-es PDUs are reordered by theirassociated queues in a reordering queue distribution entity thenreordered by sequence number per logical channel according to their TSN.A disassembly entity then disassembles the concatenated MAC SDUs and/orMAC SDU segments. A reassembly entity reassembles MAC SDU segments intothe complete MAC SDU and then directs all complete MAC SDUs to theproper higher layer entity.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawingswherein:

FIG. 1 is a prior art UTRAN MAC/e;

FIG. 2 is a prior art UTRAN MAC/es;

FIG. 3 is a prior art WTRU MAC-e/es;

FIG. 4 is a block diagram of a WTRU enhanced MAC-e/es in accordance witha first embodiment;

FIG. 5 is a block diagram of a WTRU enhanced MAC-e/es in accordance witha second embodiment;

FIG. 6 is a block diagram of a UTRAN enhanced MAC-es in accordance witha first embodiment;

FIG. 7 is a block diagram of a UTRAN enhanced MAC-es in accordance witha second embodiment;

FIG. 8 is a block diagram of a UTRAN enhanced MAC-e in accordance with afirst embodiment;

FIG. 9 is a block diagram of a UTRAN enhanced MAC-es in accordance witha first embodiment;

FIG. 10 is a block diagram of a WTRU enhanced MAC-e/es in accordancewith a third embodiment; and

FIG. 11 is a block diagram of a method of segmentation of packets at theMAC layer.

DETAILED DESCRIPTION

When referred to hereafter, the terminology “wireless transmit/receiveunit (WTRU)” includes but is not limited to a user equipment (UE), amobile station, a fixed or mobile subscriber unit, a pager, a cellulartelephone, a personal digital assistant (PDA), a computer, or any othertype of user device capable of operating in a wireless environment. Whenreferred to hereafter, the terminology “base station” includes but isnot limited to a Node-B, a site controller, an access point (AP), or anyother type of interfacing device capable of operating in a wirelessenvironment.

FIG. 4 is a block diagram of a WTRU enhanced MAC-e/es 400 in accordancewith a first embodiment. The WTRU enhanced MAC-e/es 400 comprises a HARQentity 410, a multiplexing and TSN setting entity 420, an E-TFCselection entity 430, and at least one segmentation entity 440, 440_(n).

The HARQ entity 410 is configured to store enhanced MAC-e PDUs andretransmit them. The detailed configuration of the HARQ protocol isprovided by the radio resource control (RRC) over the MAC-controlservice access point (SAP).

The multiplexing and TSN setting entity 420 is configured to concatenatemultiple MAC SDUs or segments thereof into enhanced MAC-es PDUs. In oneembodiment, the multiplexing and TSN setting entity 420 may segment aMAC SDU to fill an enhanced MAC-es PDU as instructed by the E-TFCselection entity 430 if a MAC SDU is too large to fit into a selectedpayload size for a specific logical channel.

Further, the multiplexing and TSN setting entity 420 is configured tomultiplex one or more enhanced MAC-es PDUs into a single enhanced MAC-ePDU, to be transmitted in a next TTI, as instructed by the E-TFCselection entity 430. The multiplexing and TSN setting entity 420 isfurther configured to manage and set the TSN per logical channel foreach enhanced MAC-es PDU.

The E-TFC selection entity 430 is configured to control E-TFC selectionaccording to scheduling information, relative grants and absolutegrants, received from the UTRAN via L1 signaling and a serving grantvalue signaled through RRC. The E-TFC selection entity 430 is furtherconfigured for arbitrating different flows mapped on the E-DCH. Thedetailed configuration of the E-TFC selection entity 430 is provided bythe RRC over the MAC-control SAP. As stated above, the E-TFC selectionentity 430 controls the multiplexing function of the multiplexing andTSN setting entity 420.

As stated above, the WTRU enhanced MAC-e/es comprises at least onesegmentation entity 440, 440 _(n). More specifically, there is onesegmentation entity 440, 440. for each logical channel in each WTRU. Thesegmentation entity 440, 440 _(n) is configured to segment MAC SDUs. Asshown in FIG. 4, in one embodiment, the segmentation of the MAC SDU mayoccur prior to multiplexing and TSN setting an UL transmission.

The segmentation entity 440, 440 _(n) may segment a MAC SDU if the SDUis too large to fit into a selected enhanced MAC-e payload as instructedby the E-TFC selection entity 430. For a subsequent transmission, if theremaining segment of MAC SDU is too large to fit into a selectedenhanced MAC-e payload as instructed by the E-TFC selection entity 430,this remaining segment may be segmented again. Further, the segmentationentity 440, 440 _(n) may segment a MAC SDU based on a remaining payloadfor each logical channel.

Each segmentation entity 440, 440 _(n) may comprise a buffer configuredto store a segment of a MAC SDU after the segmentation of the MAC SDU.After the segmentation of the MAC SDU, a segment of the MAC-SDU istransmitted and the remaining segment is stored in the buffer. In apreferred embodiment, each buffer contains data belonging to at most oneMAC SDU at any given time.

Alternatively, there may be only one buffer for all segmentationentities 440, 440 _(n) containing data from only one logical channel. Asa result, a MAC SDU may not be segmented for any another logical channeluntil the data in the buffer is transmitted.

Preferably, the multiplexing and TSN setting entity 420 is configured toprioritize a stored segment of a MAC SDU when creating the enhancedMAC-es PDU for the logical channel. The multiplexing and TSN settingentity 420 includes the stored segment of the MACSDU in an enhancedMAC-es PDU before requesting more data from the logical channel to whichthis MAC SDU belongs. Once all the stored MAC SDU segments are includedin an enhanced MAC-es PDU, more data may be requested from the logicalchannel. According to this embodiment, a maximum of two MAC SDU segmentsper logical channel may be included in one enhanced MAC-e PDU.

FIG. 5 is a block diagram of a WTRU enhanced MAC-e/es 500 in accordancewith a second embodiment. The WTRU enhanced MAC-e/es 500 comprises aHARQ entity 510, a segmentation, multiplexing, and TSN setting entity520, and an E-TFC selection entity 530. In contrast to the firstembodiment, the segmenting entity is incorporated with the multiplexingand TSN setting entity forming the segmentation, multiplexing, and TSNsetting entity 520. The segmentation, multiplexing, and TSN settingentity 520 may have one buffer for each logical channel. Alternatively,the segmentation, multiplexing, and TSN setting entity 520 may have onebuffer for all logical channels.

With the introduction of the segmentation entity, described above, theenhanced MAC-es PDU created may include a segmentation description orsegmentation status field in addition to a TSN field. The segmentationdescription field may indicate whether a segment is included in thecreated enhanced MAC-es PDU. In addition, the segmentation descriptionfield may indicate whether additional segments are expected.

There may be restrictions placed on the segmentation functions in theWTRU enhanced MAC-e/es. For example, any one of the followingrestrictions may be used individually or in combination with anotherrestriction to restrict segmentation functions in the WTRU enhancedMAC-e/es.

The support of segmentation functions in the WTRU enhanced MAC-e/es maybe configured for a logical channel, for a MAC-d flow, or for the entireWTRU enhanced MAC-e/es. For example, when two logical channels, thededicated control channel (DCCH) and the dedicated traffic channel(DTCH), are carried over E-DCH, segmentation functions may only beallowed for the DTCH and segmentation functions may not be allowed forthe DCCH, or vice versa. The WTRU enhanced MAC-e/es may be configured tosupport segmentation functions using L3 signaling or the WTRU enhancedMAC-e/es may be preconfigured to support segmentation functions.

In addition, logical channels that are used in states other than theCELL_DCH state may be configured not to support segmentation functions.For example, the common control channel (CCCH) may be configured not tosupport segmentation functions. Further, for a logical channel, theenhanced MAC-es may be configured such that no reordering functions orreassembly functions are performed. As a result, the enhanced MAC-es mayonly disassemble a PDU if concatenation has been performed.

As an optional embodiment, the WTRU enhanced MAC-e/es may be configurednot to insert a TSN number in the header of an enhanced MAC-e/es PDU ornot increment a TSN number in the header of an enhanced MAC-e/es PDU.Also, the UTRAN enhanced MAC-e and UTRAN MAC/es may be configured not tosupport segmentation functions.

Furthermore, the support of segmentation functions in the WTRU enhancedMAC-e/es may only be supported for scheduled or, alternatively,non-scheduled flows. For example, if a first service is mapped to anon-scheduled grant at the same time a second service is mapped to ascheduled grant, segmentation functions may only be allowed for thenon-scheduled first service instead of the scheduled second service.

Moreover, different segmentation thresholds may be defined to restrictsegmentation functions in the WTRU enhanced MAC-e/es. A minimum SDU sizemay be defined as a MAC SDU size for which segmentation is allowed suchthat any MAC SDU smaller than minimum SDU size is not be segmented. Aminimum segment size may be defined as the minimum size for MAC SDUsegments such that the WTRU enhanced MAC-e/es is restricted fromsegmenting a MAC SDU if a remaining segment is smaller than the minimumsegment size. A maximum segment size threshold may be defined as themaximum size for MAC SDU segments.

Additionally, other restrictions may be placed on the segmentationfunctions. For example, there may be limitations on the number oflogical channels that may be segmented. Further, the number of MAC SDUsegments placed in a logical channel may be limited.

FIG. 6 is a block diagram of a UTRAN enhanced MAC-es 600 in accordancewith a first embodiment. The UTRAN enhanced MAC-es 600 comprises areordering queue distribution entity 610, a reordering/combining entity620, a disassembly entity 630, and a reassembly entity 640. The MAC-esor enhanced MAC-es 600 is located in the SRNC or controlling radionetwork controller (CRNC) and handles E-DCH specification functionalitythat is not covered in the MAC-e or enhanced MAC-e in the NodeB. Morespecifically, the MAC-es and enhanced MAC-es perform the reassembly ofsegmented MAC SDUs. For each WTRU, there is one enhanced MAC-es in theSRNC.

The reordering queue distribution entity 610 is configured to routeenhanced MAC-es PDUs to a correct reordering buffer based on the SRNC orcontrolling radio network controller (CRNC) configuration.

The reordering/combining entity 620 is configured to reorder receivedenhanced MAC-es PDUs according to a received TSN and NodeB tags. TheNodeB tags may include a connection frame number (CFN) or subframenumber. After receiving the enhanced MAC-es PDU, enhanced MAC-es PDUswith consecutive TSNs are delivered to the disassembly entity 630. Eachlogical channel has a reordering/combining entity 620. Enhanced MAC-esPDUs that are received out of order may be reordered in any number ofways obvious to those of skill in the art.

The disassembly entity 630 is configured to disassemble enhanced MAC-esPDUs. The disassembly of an enhanced MAC-es PDU includes the removal ofan enhanced MAC-es header. A disassembled enhanced MAC-es PDU maycontain multiple MAC SDUs, or segments thereof.

The reassembly entity 640 is configured to reassemble segmented MAC SDUsand deliver these SDUs to a correct higher layer entity. The reassemblyentity 640 is coupled to the reordering/combining entity 620. Thereassembly entity 640 is configured to reassemble segmented MAC SDUs anddeliver these reassembled SDUs to the correct higher layer entity aftermacro-diversity reordering/combining is performed. As a result, thepackets received by the reassembly entity 640 are in order and, ifsegmented, may be recombined.

The UTRAN enhanced MAC-es 600 further comprises a macro diversityselection entity in FDD mode when there is soft handover with multipleNodeBs. As a result, the reordering/combining entity 620 receivesenhanced MAC-es PDUs from each NodeB in an E-DCH active set.

As shown in FIG. 6, in a preferred embodiment, the disassembly entity630 is located before the reassembly entity 640. The disassembly entity630 is further configured to disassemble an enhanced MAC-es PDU andforward the disassembled MAC-SDUs, or segments thereof to the reassemblyentity 640. Then, the reassembly entity 640 is configured to reassemblesegmented SDUs and forward all complete SDUs to the higher layers.

FIG. 7 is a block diagram of a UTRAN enhanced MAC-es 700 in accordancewith a second embodiment. The UTRAN enhanced MAC-es 700 comprises areordering queue distribution entity 710, a reordering/combining entity720, and a reassembly entity 730. In contrast to the first embodiment,only the reassembly entity 730 is introduced into the enhanced MAC-es700. However, the reassembly entity 730 includes the functions of thedisassembly entity described hereinbefore in FIG. 6.

FIG. 8 shows a block diagram of an enhanced MAC-e 800 and an E-DCHscheduling entity 810. As stated above, the enhanced MAC-e 800 islocated in a NodeB and controls access to the E-DCH. There is only oneE-DCH scheduling entity 810 in the NodeB. The E-DCH scheduling entity810 is configured to manage E-DCH cell resources between WTRUs. Based onscheduling requests, scheduling grants are determined and transmittedfrom the E-DCH scheduling entity 810. The enhanced MAC-e is connected tothe enhanced MAC-es. The enhanced MAC-e 800 and the E-DCH schedulingentity 810 handle HSUPA specific functions in the NodeB.

The UTRAN enhanced MAC-e 800 shown in FIG. 8 comprises an E-DCH controlentity 820 and a HARQ entity 840. The E-DCH control entity 820 isconfigured to receive scheduling requests and transmit scheduling grantsbased on the scheduling requests. The HARQ entity 840 handles the MACfunctions relating to the HARQ protocol. The HARQ entity 840 isconfigured to support multiple HARQ processes. Each HARQ process isresponsible for generating ACKs and NACKs indicating the delivery statusof E-DCH transmissions.

In contrast to the existing UTRAN MAC-e, a de-multiplexing function isremoved from the UTRAN enhanced MAC-e 800. The de-multiplexing functionis instead present in the enhanced MAC-es. As a result, both thede-multiplexing function and a reassembly function are performed in theenhanced MAC-es.

FIG. 9 is a block diagram of a UTRAN enhanced MAC-es 900. The UTRANenhanced MAC-es 900 shown in FIG. 9 comprises a reordering queuedistribution entity 910, a reordering/combining entity 920, adisassembly entity 930, a reassembly entity 940, and a de-multiplexingentity 950. The enhanced MAC-es 900 is located in the SRNC and handlesE-DCH specification functionality that is not covered in the enhancedMAC-e in the NodeB. The enhanced MAC-es 900 is connected to both theenhanced MAC-e and the MAC-d.

The reordering queue distribution entity 910 is configured to routeenhanced MAC-es PDUs to a correct reordering buffer based on the SRNCconfiguration.

The reordering/combining entity 920 is configured to reorder receivedenhanced MAC-es PDUs according to a received TSN and NodeB tags. TheNodeB tags may include a CFN or sub-frame number. After receiving theenhanced MAC-es PDU, enhanced MAC-es PDUs with consecutive TSNs aredelivered to the disassembly entity 930. Each logical channel has areordering/combining entity 920. Enhanced MAC-es PDUs that are receivedout of order may be reordered in any number of ways obvious to those ofskill in the art.

The disassembly entity 930 is configured to disassemble enhanced MAC-esPDUs. The disassembly of an enhanced MAC-es PDU includes the removal ofan enhanced MAC-es header. A disassembled enhanced MAC-es PDU maycontain multiple MAC SDUs or segments thereof.

The reassembly entity 940, as described above, is configured toreassemble segmented MAC SDUs and deliver the MAC SDUs to a correcthigher layer entity. The reassembly entity 940 is coupled to thereordering/combining entity 920. The reassembly entity 940 is configuredto reassemble segmented MAC SDUs and deliver these reassembled SDUs tothe correct higher layer entity after macro-diversityreordering/combining is performed. As a result, the packets received bythe reassembly entity 940 are in order and, if segmented, may berecombined.

In an alternative embodiment, the reassembly entity 940 is furtherconfigured to disassemble enhanced MAC-es PDUs. As a result, a separatedisassembly entity 930 may not be required.

The de-multiplexing entity 950 is configured to de-multiplex logicalchannels including enhanced MAC-e PDUs.

The UTRAN enhanced MAC-es 900 further comprises a macro diversityselection entity in FDD mode when there is soft handover with multipleNodeBs. As a result, the reordering/combining entity 920 receivesenhanced MAC-es PDUs from each NodeB in an E-DCH active set.

FIG. 10 is a block diagram of a WTRU enhanced MAC-e/es 1000 inaccordance with a third embodiment. The WTRU enhanced MAC-e/es 1000comprises a HARQ entity 1010, a multiplexing and TSN setting entity1020, an E-TFC selection entity 1030, and a segmentation and sequencenumber (SN) setting entity 1040. In contrast to the first and secondembodiments described above, a single segmentation entity, thesegmentation and SN setting entity 1040, is used for all logicalchannels. As shown in FIG. 10, the segmentation and SN setting entity1040 is located after the multiplexing and TSN setting entity 1020.

The segmentation and SN setting entity 1040 is configured to segment amultiplexed MAC SDU, if the SDU is too large to fit into a selectedenhanced MAC-e payload as instructed by the E-TFC selection entity. Fora subsequent transmission, if the remaining segment of MAC SDU is toolarge to fit into a selected enhanced MAC-e payload as instructed by theE-TFC selection entity 1030, this remaining segment may be segmentedagain. Further, the segmentation and SN setting entity 1040 may segmenta multiplexed MAC SDU based on a remaining payload for the logicalchannels. The segmentation and SN setting entity 1040 segmentsmultiplexed MAC SDUs for all logical channels.

The segmentation and SN setting entity 1040 may comprise a bufferconfigured to store a segment of a MAC SDU after the segmentation of themultiplexed MAC SDU. After the segmentation of the multiplexed MAC SDU,a segment of the multiplexed MAC SDU is transmitted and the remainingsegment is stored in the buffer for transmission in a subsequent TTI.

The segmentation and SN setting entity 1040 may further be configured toinclude a SN in a segmented and multiplexed MAC SDU. The inclusion ofthe SN may permit the UTRAN to reorder segments prior tode-multiplexing. However, the inclusion of a SN in a segmented andmultiplexed MAC SDU is optional. Further, the UTRAN may reorder segmentsbased on information provided by the HARQ entity 1010.

FIG. 11 shows a method of segmentation in an enhanced MAC-e/es sub-layerin a WTRU. When a MAC SDU is received from a higher layer that is toolarge for the selected payload for an enhanced MAC-es PDU currentlybeing created, the MAC SDU is segmented as shown in block 1101. MAC SDUsor segments of MAC SDUs are concatenated to create an enhanced MAC-es asindicated in block 1103. While creating an enhanced MAC-es PDU, MAC SDUsreceived from the higher layers may be segmented to fill an enhancedMAC-es currently being created as in block 1105. When the remainingpayload of an enhanced MAC-es PDU currently being created is smallerthan a MAC SDU received from the higher layers, the received MAC SDU maybe segmented such that a segment of the received MAC SDU fills theremaining payload available in the enhanced MAC-es PDU currently beingcreated. Multiple enhanced MAC-es PDUs are then multiplexed into asingle enhanced MAC-e PDU as shown in block 1107. The enhanced MAC-e PDUmay include MAC SDUs or segments thereof. The enhanced MAC-e PDU is thentransmitted at the next TTI as in block 1109. If an error is detected inthe transmission of the enhanced MAC-e PDU, a HARQ process retransmitsthe enhanced MAC-e PDU until successful transmission occurs as in block1111.

In a further embodiment, a MAC-d sub-layer comprises a segmentationentity. The segmentation entity in the MAC-d is configured to segmentRLC PDUs based on E-TFC selection performed at the MAC sub-layer. TheMAC-d header for segmented RLC PDUs may include a segmentation relatedinformation. For example, the MAC-d header may include a segmentationindicator. Further, the MAC-d header may include information regardingthe number of segments comprising the segmented RLC PDUs or whether moresegments are expected.

In a further embodiment, an enhanced MAC-es sub-layer is configured tomultiplex multiple logical channels into a MAC-d flow. As a result, anenhanced MAC-es PDU may contain MAC SDUs from different logical channelsbelonging to the same MAC-d flow.

Additionally, the enhanced MAC-es sub-layer is further configured toperform segmentation and TSN numbering for a MAC-d flow instead of alogical channel. As a result, the MAC-d flows may be multiplexedtogether in the enhanced MAC-e sub-layer.

Accordingly, the UTRAN enhanced MAC-e is responsible for de-multiplexingan enhanced MAC-e PDU into enhanced MAC-es PDUs and directing theenhanced MAC-es PDUs to the appropriate MAC-d flow. Further, theresponsibility of the UTRAN enhanced MAC-es modified. For example, thereordering of enhanced MAC-es PDUs is now performed for a MAC-d flow.Next, the enhanced MAC-es PDUs are reassembled and/or disassembled asdescribed above. Then, a de-multiplexing entity in the enhanced MAC-esconfigured for de-multiplexing the enhanced MAC-es PDUs into the MACSDUs and routing the MAC SDUs to a correct logical channel.

Although features and elements are described above in particularcombinations, each feature or element can be used alone without theother features and elements or in various combinations with or withoutother features and elements. The methods or flow charts provided hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable storage medium for execution by ageneral purpose computer or a processor. Examples of computer-readablestorage mediums include a read only memory (ROM), a random access memory(RAM), a register, cache memory, semiconductor memory devices, magneticmedia such as internal hard disks and removable disks, magneto-opticalmedia, and optical media such as CD-ROM disks, and digital versatiledisks (DVDs).

Suitable processors include, by way of example, a general purposeprocessor, a special purpose processor, a conventional processor, adigital signal processor (DSP), a plurality of microprocessors, one ormore microprocessors in association with a DSP core, a controller, amicrocontroller, Application Specific Integrated Circuits (ASICs), FieldProgrammable Gate Arrays (FPGAs) circuits, any other type of integratedcircuit (IC), and/or a state machine.

A processor in association with software may be used to implement aradio frequency transceiver for use in a wireless transmit receive unit(WTRU), user equipment (UE), terminal, base station, radio networkcontroller (RNC), or any host computer. The WTRU may be used inconjunction with modules, implemented in hardware and/or software, suchas a camera, a video camera module, a videophone, a speakerphone, avibration device, a speaker, a microphone, a television transceiver, ahands free headset, a keyboard, a Bluetooth® module, a frequencymodulated (FM) radio unit, a liquid crystal display (LCD) display unit,an organic light-emitting diode (OLED) display unit, a digital musicplayer, a media player, a video game player module, an Internet browser,and/or any wireless local area network (WLAN) or Ultra Wide Band (UWB)module.

What is claimed is:
 1. A wireless transmit/receive unit (WTRU)comprising: a medium access control (MAC) entity for an enhanceddedicated channel (E-DCH), the MAC entity comprising: one or moresegmentation entities configured to segment a MAC protocol data unit(PDU) on a condition that the MAC PDU is too large to fit in a payloadsize, wherein there is one segmentation entity for each logical channel;a multiplexing and a transmission sequence number (TSN) setting entityconfigured to concatenate multiple MAC PDUs and multiplex one or more ofthe concatenated MAC PDUs into a MAC PDU to be transmitted in a nexttransmission time interval (TTI), wherein the MAC PDU to be transmittedin the next TTI includes a TSN and a segmentation description field thatprovides an indication of a segmentation status of the one or more MACPDUs in the concatenated and multiplexed MAC PDU; an enhanced transportformat combination (E-TFC) selection entity configured to control themultiplexing and TSN setting entity; and a hybrid automaticretransmission request (HARQ) entity configured to store and transmitthe MAC PDU in a payload, wherein the transmitted MAC PDU includes theconcatenated and multiplexed MAC PDUs.
 2. The WTRU of claim 1, whereinthe E-TFC selection entity in the MAC entity is further configured toinstruct the at least one segmentation entity that the MAC PDU is toolarge to fit in the payload size.
 3. The WTRU of claim 1, wherein thesegmentation description field indicates whether a segment of a MAC PDUis included in the concatenated and multiplexed MAC PDU.
 4. The WTRU ofclaim 1, wherein the segmentation description field indicates whetheradditional segments of a MAC PDU are expected in a next concatenated andmultiplexed MAC PDU.
 5. The WTRU of claim 1, wherein the segmentationdescription field indicates whether the concatenated and multiplexed MACPDU include a segment of a MAC PDU.
 6. The WTRU of claim 1, wherein theat least one segmentation entity further comprises at least one bufferconfigured to store one or more remaining MAC SDU segments not includedin the payload.
 7. The WTRU of claim 6, wherein the at least one bufferis associated with the one or more segmentation entities.
 8. The WTRU ofclaim 1, wherein the multiple MAC PDUs have different sizes.
 9. The WTRUof claim 1, wherein the segmented MAC PDU is a MAC for dedicated channel(MAC-d) PDU.
 10. The WTRU of claim 1, wherein the transmitted MAC PDU isan enhanced PDU used for transmitting data on the E-DCH.
 11. A methodfor use in a wireless transmit/receive unit (WTRU) having a mediumaccess control (MAC) entity for an enhanced dedicated channel (E-DCH),the method comprising: segmenting a MAC protocol data unit (PDU) on acondition that the MAC PDU is too large to fit in a payload size;concatenating multiple MAC PDUs and multiplexing one or more of theconcatenated MAC PDUs into a MAC PDU to be transmitted in a nexttransmission time interval (TTI), wherein the MAC PDU to be transmittedin the next TTI includes a transmission sequence number (TSN) and asegmentation description field that provides an indication of asegmentation status of the one or more MAC PDUs in the concatenated andmultiplexed MAC PDU; and storing and transmitting the concatenated andmultiplexed MAC PDUs in a payload, wherein the transmitted MAC PDUincludes the concatenated and multiplexed MAC PDUs.
 12. The method ofclaim 11, further comprising determining that the MAC PDU is too largeto fit in the payload size.
 13. The method of claim 11, wherein thesegmentation description field indicates whether a segment of a MAC PDUis included in the concatenated and multiplexed MAC PDU.
 14. The methodof claim 11, wherein the segmentation description field indicateswhether additional segments of a MAC PDU are expected in a nextconcatenated and multiplexed MAC PDU.
 15. The method of claim 11,wherein the segmentation description field indicates whether theconcatenated and multiplexed MAC PDU include a segment of a MAC PDU. 16.The method of claim 11, further comprising storing one or more remainingMAC SDU segments not included in the payload.
 17. The method of claim11, wherein the multiple MAC PDUs have different sizes.
 18. The methodof claim 11, wherein the segmented MAC PDU is a MAC for dedicatedchannel (MAC-d) PDU.
 19. The method of claim 11, wherein the transmittedMAC PDU is an enhanced PDU used for transmitting data on the E-DCH.